This was an important technical assignment that was designed to force you to start to think about the direction and intensity of lighting. There is a dramatic difference between hard and soft lighting and your assignment captures that difference beautifully.
The biggest difference is that diffused lighting randomly scatters while hard light has a much more directional nature to it. The result is that hard light casts sharp shadows with clearly defined edges. As the light becomes softer and more diffused the shadow’s edge will also soften and the light will start to “mould” around your subjects or objects.
Looking at the lines of shadow and light on your pumpkins is a great example. The shadow’s lines are are clearly defined. They have sharp edges. In your soft lighting photograph however, even though there are gradients of light (i.e. the girls left side of her face is lit more brightly than the right side), the shadow does not create a harsh line and instead creates a very nice and very soft gradient into different lighting tones.
There is no one right way or wrong way. However, generally speaking people look much better under soft lighting (as your photograph showcases!). Great work.